commit fcae4ee9eb3e5816b344af652659342400a08682
from: Alexander Arkhipov <aa@manpager.org>
date: Sat Jun  8 07:17:51 2024 UTC

don't escape backslashes in cron

commit - 7030bc240475571d6fa870360fb85664bf2e475d
commit + fcae4ee9eb3e5816b344af652659342400a08682
blob - 75865eed56702dd15dbb0c4b170bc63f2b07b558
blob + a5fcf79908139aa2be295e1a17321a7321d45708
--- art/015.cron_tricks.txt
+++ art/015.cron_tricks.txt
@@ -76,20 +76,17 @@ echo(1) and printf(1).
 
 	More general approach to newlines
 
-You can use printf(1) to get newlines in your commands, though you'll
-have to escape the backslash twice:
+You can use printf(1) to get newlines in your commands:
 
-*/10 */2 * * * printf '\%s\\n\%s' "hey bob" "it's $(date +\%H:\%M)" | mail -s hey bob
+*/10 */2 * * * printf '\%s\n\%s' "hey bob" "it's $(date +\%H:\%M)" | mail -s hey bob
 
 Or if you want to have a special character standing for newline, (e.g.
 @) you can do that with tr, or sed:
 
-*/10 */2 * * * echo "hey bob@it's $(date +\%H:\%M)@Made With tr(1)" | tr @ \\\\n | mail -s hey bob
-*/10 */2 * * * echo "hey bob@it's $(date +\%H:\%M)@Made With sed(1)" | sed s/@/\\\\n/g | mail -s hey bob
+*/10 */2 * * * echo "hey bob@it's $(date +\%H:\%M)@Made With tr(1)" | tr @ \\n | mail -s hey bob
+*/10 */2 * * * echo "hey bob@it's $(date +\%H:\%M)@Made With sed(1)" | sed s/@/\\n/g | mail -s hey bob
 
-(Note the doubly-escaped backslashes in all of the above!)
 
-
 	Doing things with tmux
 
 Most tmux commands are good enough at assuming the first session they
@@ -131,7 +128,7 @@ some OpenBSD specific:
 
 - Random intervals with ~. E.g., beep at random minute every hour:
 
-~ * * * * printf \\\\b
+~ * * * * printf \\b
 
 - Command output is mailed to the crontab owner! Really awesome for
   debugging, and noticing problems early. Copious mail output is not a
@@ -154,11 +151,8 @@ where cron can run an X11 program. OpenBSD allows you 
 specific, and get the display each user is logged on to via who(1).
 Here's how to use it:
 
-0 12 * * * DISPLAY=`who | awk -vu=$USER '$1 == u && $NF ~ /^[(]:[0-9]+[)]$/ {print substr($NF, 2, length($NF)-2); exit}'` /usr/X11R6/bin/xmessage "it's 12 o'clock"
+0 12 * * * DISPLAY=`who | awk -vu=$USER '$1 == u && $NF ~ /^\(:[0-9]+\)$/ {print substr($NF, 2, length($NF)-2); exit}'` /usr/X11R6/bin/xmessage "it's 12 o'clock"
 
-(I put parantheses into brackets here to avoid doubly-escaping
-the backslashes.)
-
 If you have many regularly-running X11 cronjobs, you can save the
 who(1)-filtering bit in a script (e.g. ~/bin/getdisp):